Amazon has dog tags that blink. We had a black lab that liked hiding in the bushes in the backyard. You could call and call and look but unless she wanted to be found it wasn't happening. Enter the blinking tag.

We have a red tri Australian shepherd. He blends in the woods here in East Tn so well it's scary how fast he can disappear. I got some blaze orange material, sewed a tube & slipped his collar through it. Now I can actually see him at a distance.